No abstract

Polymer-derived ceramics demonstrate great potential as lithium-ion battery anode materials with good cycling stability and large capacity. SiCNO ceramic nanoparticles are produced by the pyrolysis of polysilazane nanoparticles that are synthesized via an oil-in-oil emulsion crosslinking and used as anode materials. The SiCNO nanoparticles have an average particle size of around 9 nm and contain graphitic carbon and Si3N4 and SiO2 domains. Composite anodes are produced by mixing different concentrations of SiCNO nanoparticles, edge-functionalized graphene oxide, polyvinylidenefluoride, and carbon black Super P. The electrochemical behavior of the anode is investigated to evaluate the Li-ion storage performance of the composite anode and understand the mechanism of Li-ion storage. The lithiation of SiCNO is observed at ∼0.385 V versus Li/Li+. The anode has a large capacity of 705 mA h g–1 after 350 cycles at a current density of 0.1 A g–1 and shows an excellent cyclic stability with a capacity decay of 0.049 mA h g–1 (0.0097%) per cycle. SiCNO nanoparticles provide a large specific area that is beneficial to Li+ storage and cyclic stability. In situ transmission electron microscopy analysis demonstrates that the SiCNO nanoparticles exhibit extraordinary structural stability with 9.36% linear expansion in the lithiation process. The X-ray diffraction and X-ray photoelectron spectroscopy investigation of the working electrode before and after cycling suggests that Li+ was stored through two pathways in SiCNO lithiation: (a) Li-ion intercalation of graphitic carbon in free carbon domains and (b) lithiation of the SiO2 and Si3N4 domains through a two-stage process.

No abstract

No abstract

The objective of this work is to investigate the salt water effects on fatigue degradation, and stress-life relationship. A series of reversed fatigue experiments were conducted on (carbon+ glass) / PMMA of salt water environments. Results indicate that the composite degrade during cycling. Exposure to salt water (salt water is used to simulate the sea water) provides the most significant reduction in fatigue life. The corrosion environment reduces the fatigue strength by 61% compared to dry fatigue. Based on previous damage model [16], corrosionfatigue nonlinear damage model is presented in this paper, which contains one material constant; the inverse slope (α) of the S-N curve. Six specimens of two levels loading of composite material were used to verify the present model; the results showed that the predicted life is in good agreement with the experimental results.